1. Field of the Invention
The present invention relates in general to coating compounds for an imitation pearl, more particularly, to compounds for an under coat (A), a mid coat (B) and a top coat (C) of the imitation pearl, in which the compounds for the under and mid coats (A) and (B) of the imitation pearl are prepared b dissolving CELLULOID into a mixed solution of acetone and ethylacetate and another mixed solution of butylacetate and amylacetate, and adding a pigment to the CELLULOID solution, and the compound for the top coat (C) of the imitation pearl is prepared by dissolving CELLULOID into a mixed solution of ethylacetate and butylacetate and adding a pigment to the CELLULOID solution. CELLULOID is a registered trademark of the Celluloid Manufacturing Company of Newark, N.J.
Compared to the related art coating compounds for imitation pearls (e.g., basic lead carbonate), the coating compounds of the present invention are nontoxic and environmentally friendly. Also, compared to the typical environmentally friendly compounds like titanium dioxide or ethylacetate compounds, the coating compounds of the invention provide excellent colors and luster to the imitation pearls.
2. Description of the Related Art
Industrial development has brought positive changes on ornaments and raised more interests in accessories. As people live in more comfortable circumstances than the past, their interests in ornaments and accessories have grown naturally.
Imitation pearls are by far the best of all other accessories in that they can be mass produced, and are no way inferior to natural pearls in terms of the texture. Application range of the imitation pearls is also broad, including accessories, necklaces, rings, brooches, toys and so on.
To make imitation pearls for ornamental purposes, cellulose nitrate (or simply, cellulose) is dissolved in diverse solvents, and pigments are added thereto. Then, resin beads are coated with the mixture of the cellulose solution and the pigments.
In the past, basic lead carbonate (2PbCO3 Pb (OH)2), which is a compound of a lead (Pb)-containing neutral salt and a hydroxide, was usually used for the pigment to be added to the cellulose solution. Although the basic lead carbonate was effective for creating almost same texture and luster with natural pearls, it had deadly effects on a human body and was a major environmental contaminant.
To resolve the above-described problems, a new technique has been recently proposed. According to the new technique, cellulose was dissolved in a solvent of acetone or butylacetate, and a harmless pigment bismuthoxychloride (BiOCl), was added to the cellulose solution.
For instance, Korean patent publication No. 1996-13573 (published on Oct. 9, 1996) disclosed a method for manufacturing nontoxic imitation pearls. According to the disclosed method, nitrocellulose is dissolved into acetone, butylacetate, and ethylacetate, and then finished up by titanium dioxide and bismuthoxychloride.
The above method, however, turned out to be disadvantageous because when nitrocellulose itself was used, solubility and dispersibility of pigments for imitational pearls were poor. Also, the imitation pearls made of nitrocellulose were easily turned to yellow because of nitrocellulose being very sensitive to ultraviolet rays. Although there was another technique introduced to get the same texture and physical properties with natural pearls by mixing titanium dioxide with a specific pigment (highlight pearl green), its manufacturing process was very complicated, and matching appropriate components and contents therefor was often failed. As a result, it seemed to be almost impossible to manufacture imitation pearls having gentle and bright colors like natural pearls, and this inferiority only deteriorated merchantability of the imitation pearls. What was worse that final product had 50 ppm of lead, making the imitation pearls toxic to human body.